This application is based on Japanese Patent Application No. Hei 11-224141 filed on Aug. 6, 1999, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a fluid injection nozzle having a plate in which a fluid injection hole is formed. For instance, the present invention applies to a fuel injection valve for supplying fuel to an internal combustion engine (engine).
2. Description of Related Art
DE 19636396A1 discloses fuel injector having a plate in which a plurality of through holes are formed as fuel injection orifices. Such a plate type injectors are effective to generate a plurality of fuel jets. In this arrangement, fuel flows along an inclined surface formed by a valve seat. However, some of the through holes are opened on an imaginary line where a surface of the plate crosses an extended line of the inclined surface. Therefore, fuel flowing along the inclined surface directly flows into the through holes. Therefore, fuel is insufficiently atomized.
U.S. Pat. No. 4,907,748, U.S. Pat. No. 5,762,272 and WO 98/34026 disclose the fuel injectors having flat chambers just upstream the through holes. Such a chamber provides a compound fuel flow just upstream the through hole and is effective to atomize fuel. However, there is a possibility to spoil an atomization by a collision of injected fuel columns at just after the through holes. Here, the fuel column is a shape of fuel before fuel is atomized by collision with air. Further, a shape of a wall defining the chamber is important to define a fuel flow at an inlet of the through hole, since the fuel atomization is affected by the fuel flow flowing along the plate. However, WO 98/34026 does not provide a surface having a sufficient flatness and a size to atomize fuel.
The present invention addresses these drawbacks by providing an improved fluid injection nozzle arrangement.
It is therefore an object of this invention to improve an atomization of fluid.
It is a further object of this invention to provide a fluid injection nozzle in which a collision of injected fluid columns is avoided.
According to a first aspect of the present invention, the fluid injection nozzle has a chamber for controlling a fluid flow to a through hole formed on a plate. Fluid flowing along an inner surface of a valve body is inclined to meet and collide at a center region of the plate. Therefore, fluid turns its direction and flows along the plate. Specifically, the chamber is flat and is extended more than a diameter of the through hole at an outside of the through hole. Therefore, fluid flows along the chamber for a sufficient distance and reaches the through hole from all directions and collides at an inlet of the through hole. As a result, fluid injected from the through hole has a lot of turbulences and is finely atomized. Further, an inlet of the through hole opens at an outer area of a projected area which is defined by projecting a downstream end opening of the inner surface of the valve body. Therefore, the through holes are separately arranged to avoid a collision of columns of fluid injected from the through holes.
According to another aspect of the present invention, a plate has an inner through hole and an outer through hole located both side of an imaginary line. Here, the imaginary line is defined by crossing a surface of the plate and a line extended along the inner surface of the valve body. Therefore, the inner through hole and the outer through hole are mainly influenced by fluid flows having different directions. As a result, columns of injected fluid are directed in different directions and a collision of the columns is avoided.